Specific ion flows: a novel signal mediating stem cell-niche communication

描述（由申请人提供）：损伤后的模式再生和正常细胞周转期间的形态维持需要成体干细胞的参与。为了了解并最终学会控制这些过程以用于生物医学应用，有必要确定干细胞与其相邻细胞通信的分子机制。干细胞需要这样的交流才能知道何时、何地以及如何分化。由于基本的细胞控制机制是广泛保守的，并且因为我们相信在可识别的成体干细胞群体的分子研究系统中可以取得根本性的进展，我们建议通过利用一个强大的模型系统来研究干细胞在体内的相互作用：地中海涡虫Schmidtea。这些复杂的扁虫能够用一种可识别的成体干细胞群——新生细胞——来替换身体的任何部位。这是一个理想的系统，其中研究分子信号发送到和从新母细胞。与该领域对生化因素的关注形成对比和补充，我们的实验室研究内源性离子流、pH和电压梯度在控制细胞增殖、迁移和分化中的作用。我们将测试这样一个假设，即控制干细胞在其环境中的行为的局部和远程信号的很大一部分是生物电的，包括特定离子通道和泵活性的生理结果。我们将描述几个通道、泵和间隙连接在控制干细胞位置信息及其在再生过程中的作用。我们提出了两个主要目标：1)分子验证（使用RNAi）参与新细胞介导事件的几个候选通道和泵蛋白，然后对它们的表达进行分析，并详细描述它们在再生和重塑中的作用；2)干细胞在分化的不同阶段的生物电学特性的表征，以及在体内控制新细胞运动、增殖和分化的功能技术的发展。我们的研究小组在几个脊椎动物和无脊椎动物系统的胚胎发育和再生领域所积累的专业知识，将使我们在揭示干细胞调控的新方面取得快速而重要的进展，并将导致一套全新的干细胞信号控制的高回报结果，最终将用于推动旨在诱导患者成人细胞再生的生物医学应用。这项工作非常适合癌症、衰老、生物医学成像和生物工程研究所，因为我们建议使用新的成像和生物物理操作技术来实现医学应用，在这些应用中，可以诱导成体干细胞适当地取代衰老、受损或癌变的组织。我们的工作将引导我们了解成体干细胞是如何让一些动物完美地修复它们身体的任何部位的。这些信息将用于开发方法，从而在受伤、衰老或肿瘤生长的人类患者中诱导组织、器官和附属物的再生。

DESCRIPTION (provided by applicant): The regeneration of pattern following injury and the maintenance of form during normal cellular turnover requires the participation of adult stem cells. In order to understand and ultimately learn to control these processes for biomedical applications, it is necessary to identify the molecular mechanisms by which stem cells communicate with their neighbors. Such communication is needed for stem cells to know where, when, and how to differentiate. Because fundamental cellular control mechanisms are widely conserved, and because we believe fundamental progress can be made in systems that are amenable to the molecular investigation of a recognizable adult stem population, we propose study stem cell interactions in vivo by capitalizing on a powerful model system: the planarian Schmidtea mediterranea. These complex flatworms are able to replace any part of their body using a recognizable adult stem cell population: the neoblasts. This is an ideal system in which to investigate the molecular signals sent to and from neoblasts. In contrast and complement to the field's focus on biochemical factors, our lab studies roles of endogenous ion flows, and pH and voltage gradients in controlling cell proliferation, migration, and differentiation. We will test the hypothesis that a large component of the local and long-range signals controlling stem cell behavior within their environment is bioelectrical, consisting of the physiological results of specific ion channel and pump activity. We will characterize the involvement of several channels, pumps, and gap junctions in controlling stem cell positional information and their contribution during regeneration. We propose two main aims: 1) molecular validation (using RNAi) of several candidate channel and pump proteins involved in neoblast-mediated events, followed by their expression analysis and a detailed characterization of their roles in regeneration and remodeling; and 2) characterization of the bioelectrical properties of stem cells as they progress through the different phases of differentiation and development of functional techniques to control neoblast movement, proliferation, and differentiation in vivo. The expertise which our group has developed with this field in embryonic development and regeneration in several vertebrate and invertebrate systems will allow rapid and important progress to uncover novel aspects of stem cell regulation, and will result in the high-reward outcome of an entirely new set of controls of stem cell signaling, which ultimately will be used to drive biomedical applications aiming to induce regeneration in adult cells of the patient. This work is an ideal fit for the Cancer, Aging, and Biomedical Imaging and Bioengineering Institutes because we propose to use novel imaging and biophysical manipulation techniques to enable medical applications in which adult stem cells can be induced to properly replace aging, damaged, or cancerous tissue. Our work will lead to the understanding of how adult stem cells allow some animals to perfectly repair any part of their body. This information will be used to develop methods whereby regeneration of tissues, organs, and appendages may be induced in human patients following injury, aging, or tumor growth.